1. Field of the Invention
The invention relates generally to wireless electronic communications and more particularly to antenna tuning systems and methods.
2. Background
In a communication system with different transmit and receive frequencies, mobile station antenna efficiency is a balance between optimization for the transmit frequency and optimization for the receive frequency. Under typical operating conditions, the typical antenna efficiency balance allows for the best use of the transmit and receive resources. However, commonly, conditions occur in which the typical antenna efficiency balance is not preferred. In such conditions, it can be said that the forward and reverse links are not balanced.
The forward link is the communication link for data (voice data or other data) travelling from a base station transmitter to a mobile station receiver. The reverse link is the communication link for data (voice data or other data) from the mobile station transmitter to the base station receiver.
A first example of a forward and reverse link imbalance is when fading conditions may reduce either the forward link or the reverse link reception. In a second example, the antenna efficiency balance between the transmit and receive frequencies may not be ideal, as a result of some slowly changing parameter or even as a result of a fixed parameter. For example, the antenna matching circuit, or some other hardware component, may have been manufactured or calibrated in a way that provides a non-ideal balance between the transmit and receive frequencies. Alternatively, the antenna efficiency balance may become non-ideal under certain temperature conditions, such as, for example, when high temperatures result from extended continuous use.
In a third example, the forward and reverse link may become imbalanced as a result of performance reduction caused by environmental changes around the mobile station. For example, the antenna may be covered by the user's hand or the mobile station may be placed on a metallic table.
In a fourth example, the typical antenna efficiency balance may not be preferred because of the forward and reverse link loading of the communication system at a particular time. For example, the mobile station may be transmitting or receiving only for some time periods. As another example, the wireless communication system may be overloaded in the forward link relative to the reverse link at a particular time. The communication system might be overloaded in the forward link if, for example, data is being transmitted from a base station simultaneously to many users, but relatively few users are transmitting data to the base station.